Facts about the animal kingdom

When is a Cat an Adult and When do They Stop Growing?

Josie F. Turner
By Josie F. Turner, Journalist specialized in Animal Welfare. June 3, 2019
When is a Cat an Adult and When do They Stop Growing?

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There is no doubt over the adorability of kittens. While they will eventually turn into a cute adult cat, it can seem their kitten stage passes by in moments. Cats go through various stages in their development process, evolving as much in physical appearance as maturity and temperament. Each stage is unique, but when is a cat an adult? And when do they stop growing and develop completely? AnimalWised delves into the different stages of a kitten's development into adulthood so we can know how to care for them more appropriately as they grow.


  1. At what age do cats stop growing?
  2. When do cats stop growing according to breed type?
  3. At what age do cats stop playing?
  4. Cat weight chart according to age
  5. When do cats reach sexual maturity?

At what age do cats stop growing?

Kittens need to proceed through various stages before they become adult cats. There is some debate among zoologists (animal biologists) over the exact criteria of when they stages begin and end. Despite this ongoing discussion, we can differentiate between the 5 fundamental stages of growth in cats:

  • Birth and first weeks of life: the kitten is newborn and weighs very little. They are unable to open their eyes until around 14-15 days after delivery. Up until this point, their mobility and autonomy is severely reduced. This means they rely on their mother for everything, including warmth, feeding and even stimulation for defecation.
  • First month: after three weeks the kitten will begin the weaning process whereby they start to consume solid food in addition to their mother's breast milk. They also learn to become more independent as they start to become more mobile and play with their siblings.
  • Second month: by this time, the kitten should already be able to eat on their own. This is when the fundamental stage of socialization takes place. The reason for the importance of this stage is because it is when the animal comes in contact with other animals and people. If this stage does not pass in a healthy way, it can mean they learn incorrectly how to relate to others. Behavioral problems later in life may occur. A healthy socialization process should result in an adult cat with a friendly and sociable nature.
  • Six months to a year: during this period, the cat should adopt a more definitive size and shape as they officially become a young adult. They usually begin to grow more relaxed, although they may still act up when craving food or engaging in play activity. If we are unsure of when a cat stops growing, then you can see that this point is when the cat's morphology (physical stature) begins to stabilize. This may take more or less time depending on the breed of the individual animal.
  • 1 to 3 years: although a cat may be considered an adult after one year of age, the stage up to three years is similar to what we would consider human adolescence. They may be a little more rebellious as they settle into their adulthood, growing less so as they age and starting to become comfortable in the family environment.
  • Adult stage: once they grow past the critical stage of young adulthood, our cats will adopt a definitive character. Once the cat is fully mature, they should settle into a balanced and clam attitude toward others.

After reviewing the different stages of early feline development, we can see that a cat is physically considered and adult after about 1 year of age. It is not until around 3 years of age that the cat's character and temperament become more stable and balanced. While there are other factors which will influence a cat's adult character (such as genetics or traumatic experiences), healthy experiences during these developmental stages should result in a healthy adult character. Bad experiences can lead to the contrary. One important example is removing a kitten from their mother and siblings before they are properly weaned and socialized.

When do cats stop growing according to breed type?

Although the growth of cats is similar for all domestic cat breeds, there are some variances when we compare them. This mainly has to do with the size of a particular cat breed as larger cats tend to take a little more time to develop into adult cats.

For example, so-called giant cat breeds such as the Maine Coon may take closer to 4 years before they reach their final size. British Shorthair cats are also relatively slow growing and taking up to 3 years before they reach their final adult dimensions.

On the other hand, smaller sized cat breeds may reach their full adult size earlier and medium to large cats a little later. This is why smaller cat breeds such as the Persian or Siamese cat usually reach full growth around the 1 year mark and cats like the European Shorthair may take closer to 2 years to reach full development.

When is a Cat an Adult and When do They Stop Growing? - When do cats stop growing according to breed type?

At what age do cats stop playing?

It is more common for kittens to be more active and playful than adults. This will, to a large extent, depend on the particular character of each cat. While every cat is an individual, certain breed types are more prone to hyperactivity than others.

In general terms, cats are more likely to spend the majority of their time playing non-stop from around 1.5 to 2 months of age. The greatest period of activity generally occurs at around 6 to 7 months of age. During this time they may be more boisterous and may even be considered hyperactive. However, they will want to play extensively until about a year of life.

Although play behavior may reach its zenith earlier on, this doesn't mean a cat won't want top play throughout their lives. This is why it is so important to state that a cat will want to play more or less according to the individual. Some breeds are known to play more than others, but this mean there aren't many exceptions. The most important thing is to keep them physically and mentally engaged. This means we need to offer them certain toys, intelligence games, scratching posts and much more to keep them happy and healthy. For more details, you can take a look at our article on 10 games to entertain my cat.

Cat weight chart according to age

Although a cat's weight will depend on their breed, diet and other factors, we can establish what are the average weights of cats according to the age of the feline. Always, if we are in any doubt over the weight of our cat, we need to consider its overall state of health. A cat which is over the average weight of a cat runs the risk of obesity. Felines which are severely underweight may be afflicted with one of numerous pathologies. When unsure about our cat's health, we will need to take them to the veterinarian to confirm diagnosis.

When is a Cat an Adult and When do They Stop Growing? - Cat weight chart according to age

When do cats reach sexual maturity?

An important factor in a cat's developmental stages is their sexual maturity. When they reach this stage, they will start looking for a mate and it will have a significant impact on their behavior. There are many different variables, but generally, female will reach sexual maturity when they reach 80% of their adult weight. As we have seen, different breeds belong to different weight classes. For this reason, a female cat will generally reach sexual maturity between 5 and 12 months of age.

Male cats are not necessarily beholden to weight. On average, they will reach sexual maturity at a bout 5 months of age. However, the breed will have a bearing on what time this occurs. Siamese cats may reach sexual maturity as early as 4 months and Persian cats may take up to a year to reach the same milestone.

When a female reaches sexual maturity, they will eventually enter their estrus cycle (also known as the heat period). This means they can grow very frustrated until they are able to mate. However, mating will likely lead to unwanted pregnancy. Sexually mature males can also grow more aggressive and display problematic behavior such as spraying after they reach sexual maturity. For this reason and others, veterinarians recommend sterilizing your cats.

If you want to read similar articles to When is a Cat an Adult and When do They Stop Growing?, we recommend you visit our Facts about the animal kingdom category.

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When is a Cat an Adult and When do They Stop Growing?